Many roller blinds include a clutch mechanism that is driven by a cord or chain to impart rotational movement to the roller tube for purposes of winding or unwinding blind fabric. Roller blind clutches typically include a sprocket that is situated between a back plate and a cover plate. The cover plate commonly encases at least a portion of the outer side and circumferential surfaces of the sprocket. The rope or chain of the blind is received about the sprocket, between the back and cover plates. When the blind is installed a stopper is typically fastened to the chain or cord to govern the extent of the rotational movement of the sprocket in a particular direction. That is, to “set” the maximum amount of blind fabric that can be unwound from the roller tube a stopper may be secured to the chain or cord at a position that causes the stopper to contact the clutch's back plate and/or cover plate when a desired amount of blind fabric has been unwound. The contact between the stopper and the clutch plate or plates prevents the receipt of further chain or cord about the sprocket and thereby prevents further rotation of the sprocket. To that end, the stoppers are usually larger than the diameter of the chain or cord and can be in the shape of a ball or a barrel, but could also be various other shapes.
For aesthetic purposes, many consumers and retailers of roller blinds prefer stoppers in the shape of balls. In addition, consumers generally prefer small ball stoppers as they look less intrusive on the chain or cord as it hangs downwardly from the roller blind. Smaller ball stoppers can also be slightly cheaper to manufacture than larger ones. Unfortunately, it has been found that small ball stoppers have a tendency to become jammed between the back plate and the clutch cover plates. In some instances the jamming of the ball stopper between the back and cover plates can necessitate the removal of the blind from the end brackets and a disassembly of the clutch mechanism in order to release the stopper. In other cases, if sufficient tension is applied to the chain or cord the small ball stopper can become wedged between the back plate and the clutch cover plate, causing the plates to be displaced outwardly from one another to a degree that can cause the chain or cord to slip. The jamming of the ball stopper between the cover plates could also potentially damage the clutch.